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Commit 0563e3b1 authored by Ruchir Rastogi's avatar Ruchir Rastogi
Browse files

statsd checks permissions using SCS 

The checkCallingPermission function is not supported by libbinder_ndk.
To circumvent this issue, statsd will now ask StatsCompanionService
(SCS) to do that check using a synchronous Binder call. Once
libbinder_ndk does support checkCallingPermission, this workaround will
be unnecessary.

Test: m -j
Test: atest GtsStatsdHostTestCases
Bug: 145566180
Change-Id: I11f0e82f88aa5921cf531fd041b0a18d3a26a0a0
parent e0206059

apex/statsd/aidl/android/os/IStatsCompanionService.aidl

+7 −0
Original line number Diff line number Diff line
@@ -61,4 +61,11 @@ interface IStatsCompanionService { 


    /** Tells StatsCompaionService to grab the uid map snapshot and send it to statsd. */

    oneway void triggerUidSnapshot();



    /**

     * Ask StatsCompanionService if the given permission is allowed for a particular process

     * and user ID. statsd is incapable of doing this check itself because checkCallingPermission

     * is not currently supported by libbinder_ndk.

     */

    boolean checkPermission(String permission, int pid, int uid);

}

apex/statsd/service/java/com/android/server/stats/StatsCompanionService.java

+5 −0
Original line number Diff line number Diff line
@@ -516,6 +516,11 @@ public class StatsCompanionService extends IStatsCompanionService.Stub { 
        }

    }



    @Override // Binder call

    public boolean checkPermission(String permission, int pid, int uid) {

        StatsCompanion.enforceStatsCompanionPermission(mContext);

        return mContext.checkPermission(permission, pid, uid) == PackageManager.PERMISSION_GRANTED;

    }



    // Statsd related code

cmds/statsd/src/StatsService.cpp

+28 −10
Original line number Diff line number Diff line
@@ -30,7 +30,6 @@ 
#include <android-base/stringprintf.h>

#include <android-base/strings.h>

#include <binder/IPCThreadState.h>

#include <binder/IServiceManager.h>

#include <binder/PermissionController.h>

#include <cutils/multiuser.h>

#include <dirent.h>
@@ -77,6 +76,25 @@ static binder::Status exception(uint32_t code, const std::string& msg) { 
    return binder::Status::fromExceptionCode(code, String8(msg.c_str()));

}





static bool checkPermission(const char* permission) {

    sp<IStatsCompanionService> scs = getStatsCompanionService();

    if (scs == nullptr) {

        return false;

    }



    bool success;

    pid_t pid = IPCThreadState::self()->getCallingPid();

    uid_t uid = IPCThreadState::self()->getCallingUid();



    binder::Status status = scs->checkPermission(String16(permission), pid, uid, &success);

    if (!status.isOk()) {

        return false;

    }

    return success;

}





binder::Status checkUid(uid_t expectedUid) {

    uid_t uid = IPCThreadState::self()->getCallingUid();

    if (uid == expectedUid || uid == AID_ROOT) {
@@ -97,11 +115,11 @@ binder::Status checkDumpAndUsageStats(const String16& packageName) { 
    }



    // Caller must be granted these permissions

    if (!checkCallingPermission(String16(kPermissionDump))) {

    if (!checkPermission(kPermissionDump)) {

        return exception(binder::Status::EX_SECURITY,

                StringPrintf("UID %d / PID %d lacks permission %s", uid, pid, kPermissionDump));

    }

    if (!checkCallingPermission(String16(kPermissionUsage))) {

    if (!checkPermission(kPermissionUsage)) {

        return exception(binder::Status::EX_SECURITY,

                StringPrintf("UID %d / PID %d lacks permission %s", uid, pid, kPermissionUsage));

    }
@@ -285,7 +303,7 @@ status_t StatsService::onTransact(uint32_t code, const Parcel& data, Parcel* rep 
 * TODO: Come up with a more robust method of enacting <serviceutils/PriorityDumper.h>.

 */

status_t StatsService::dump(int fd, const Vector<String16>& args) {

    if (!checkCallingPermission(String16(kPermissionDump))) {

    if (!checkPermission(kPermissionDump)) {

        return PERMISSION_DENIED;

    }

    int lastArg = args.size() - 1;
@@ -914,7 +932,7 @@ status_t StatsService::cmd_clear_puller_cache(int out) { 
    IPCThreadState* ipc = IPCThreadState::self();

    VLOG("StatsService::cmd_clear_puller_cache with Pid %i, Uid %i",

            ipc->getCallingPid(), ipc->getCallingUid());

    if (checkCallingPermission(String16(kPermissionDump))) {

    if (checkPermission(kPermissionDump)) {

        int cleared = mPullerManager->ForceClearPullerCache();

        dprintf(out, "Puller removed %d cached data!\n", cleared);

        return NO_ERROR;
@@ -927,7 +945,7 @@ status_t StatsService::cmd_print_logs(int out, const Vector<String8>& args) { 
    IPCThreadState* ipc = IPCThreadState::self();

    VLOG("StatsService::cmd_print_logs with Pid %i, Uid %i", ipc->getCallingPid(),

         ipc->getCallingUid());

    if (checkCallingPermission(String16(kPermissionDump))) {

    if (checkPermission(kPermissionDump)) {

        bool enabled = true;

        if (args.size() >= 2) {

            enabled = atoi(args[1].c_str()) != 0;
@@ -1314,12 +1332,12 @@ Status StatsService::sendBinaryPushStateChangedAtom(const android::String16& tra 
    // Root, system, and shell always have access

    if (uid != AID_ROOT && uid != AID_SYSTEM && uid != AID_SHELL) {

        // Caller must be granted these permissions

        if (!checkCallingPermission(String16(kPermissionDump))) {

        if (!checkPermission(kPermissionDump)) {

            return exception(binder::Status::EX_SECURITY,

                             StringPrintf("UID %d / PID %d lacks permission %s", uid, pid,

                                          kPermissionDump));

        }

        if (!checkCallingPermission(String16(kPermissionUsage))) {

        if (!checkPermission(kPermissionUsage)) {

            return exception(binder::Status::EX_SECURITY,

                             StringPrintf("UID %d / PID %d lacks permission %s", uid, pid,

                                          kPermissionUsage));
@@ -1410,12 +1428,12 @@ Status StatsService::sendWatchdogRollbackOccurredAtom(const int32_t rollbackType 
    // Root, system, and shell always have access

    if (uid != AID_ROOT && uid != AID_SYSTEM && uid != AID_SHELL) {

        // Caller must be granted these permissions

        if (!checkCallingPermission(String16(kPermissionDump))) {

        if (!checkPermission(kPermissionDump)) {

            return exception(binder::Status::EX_SECURITY,

                             StringPrintf("UID %d / PID %d lacks permission %s", uid, pid,

                                          kPermissionDump));

        }

        if (!checkCallingPermission(String16(kPermissionUsage))) {

        if (!checkPermission(kPermissionUsage)) {

            return exception(binder::Status::EX_SECURITY,

                             StringPrintf("UID %d / PID %d lacks permission %s", uid, pid,

                                          kPermissionUsage));